<html>
    <body>
        <div>some text</div>
        <div id="has-open"></div>
        <div id="has-closed"></div>
        <div id="has-other"></div>
        <script>
            (function makeShadowDOM() {
                document
                  .getElementById("has-open")
                  .attachShadow({ mode: 'open' });
                document
                  .getElementById("has-closed")
                  .attachShadow({ mode: 'closed' });
                // has-other shadow dom should not get created,
                // so parsing the html tag should still succeed
                document
                  .getElementById("has-other")
                  .attachShadow({ mode: 'nonsense-mode-does-not-exist' });
            })()
        </script>
    </body>
</html>

